DESCRIPTION (Verbatim from the Applicant's Abstract): We propose to continue to develop and test a self-contained light delivery device for use in photodynamic therapy (PDT) for Barrett's esophagus. This device employs distally located semiconductor lasers at the end of a thin coaxial cable inserted into a balloon catheter. In Phase I, we successfully developed prototype units that produced sufficient light for PDT treatment and evaluated different scattering media to increase the uniformity of the light emission. In Phase II, we intend to design enhancements that produce uniform light distribution and increase the illuminator's flexibility. A light and fluorescence detection system will be incorporated into the balloon's wall. Unit will be tested for safety and efficacy in an animal model. A significant advantage to this source design is that individual segments or spot locations across the illuminator can be turned on or off and the intensity changed during treatment. The light and fluorescence detection systems will allow more uniform treatment and help optimize treatment parameters (fluence, fluence rate, photosensitizer dose, and photosensitizer/light interval) to maximize the PDT effect and minimize toxicity. The diode illuminator will be capable of changing light dosing parameters to fit optimal conditions for any situation including the use of different photosensitizing compounds. PROPOSED COMMERCIAL APPLICATION: Not Available